7006 is good for top end. Laggy on the street. K27S is good for bottom & midrange, 7200 good for midrange, HF good for midrange and top end.
Cams need to follow the turbo. For good midrange use an SC or like. For top end use a 964 or like.
The 915 will not stand up to track use much past 300 ft/lb torque. Too much heat. You can outfit with spraybars, cooler and WEVO but may spend more than it's worth. 930/4spd with low R&P is a good option for medium power cars.